The present disclosure relates to semiconductor light-emitting devices using semiconductor light-emitting elements which consume relatively large electric power.
Semiconductor light-emitting devices using a semiconductor light-emitting element, such as a semiconductor laser element made of a (In, Al, Ga, P) based, (In, Al, Ga, As) based, or (In, Al, Ga, N) based compound semiconductor have been actively developed as a light source of image display devices such as a laser display or a projector, an excitation light source of a solid light source for illumination, and a light source of processing equipment for industrial use, such as a laser scribing device or a thin film annealing device. These semiconductor light-emitting devices emit very high energy light whose optical output exceeds 1 W. The electric power consumed by the semiconductor light-emitting elements accordingly increases, and the amount of heat dissipated from the semiconductor light-emitting elements also increases. Thus, various measures need to be taken on packages to which the semiconductor light-emitting elements are mounted.
One of structures of packages of most commonly used semiconductor light-emitting devices at present is a so-called CAN type which includes a disc-like base member to be fixed to an external member, and in which a post for fixing a semiconductor light-emitting element vertically with respect to a principal surface of the base member, and a lead pin for applying electricity to an anode or a cathode of the semiconductor light-emitting element are attached to the base member. For example, a semiconductor light-emitting element is mounted on the CAN type package, with a ceramic (e.g., AlN) submount interposed therebetween, and a lead and the semiconductor light-emitting element are electrically connected together by a fine gold wire, thereby forming a semiconductor light-emitting device.
Techniques for particularly improving heat dissipation properties in the above conventional package structure are disclosed in the following Patent Documents 1, 2 and 3.
First, a semiconductor light-emitting device disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2005-032937) will be described with reference to FIG. 18. FIG. 18 is a package portion of a light-emitting device 700, in which a post 705 is adhered to a surface of a disc-like base 715 with an adhesive 714, and in which three leads 716, 717 and 718 penetrate the front and back surfaces of the base 715. A submount 703 is attached to the principal surface of the post 705 with the adhesive 704 interposed therebetween. An electrode 708 is provided on the principal surface of the submount 703. A nitride semiconductor laser element 701 is adhered to the electrode 708 with solder 702 interposed therebetween. A light-emitting portion 706 of the nitride semiconductor laser element 701 is on the submount 703 side. A square U-shaped heat sink 711 is adhered to a surface of the nitride semiconductor laser element 701 which is opposite to the light-emitting portion 706, with the recess of the U-shape facing the principal surface of the submount 703. For example, the bottom face of the recess of the heat sink 711 is adhered to the upper surface of the nitride semiconductor laser element 701 with an adhesive 712 interposed therebetween. Further, the two outside lower surfaces of the heat sink 711 are adhered to the principal surface of the post 705 with an adhesive 713 interposed therebetween.
In this structure, properties of the heat dissipation from the nitride semiconductor laser element 701 to the base 715 are improved to some extent, but are not enough because the length of the post 705 needs to be sufficiently longer than the length of the nitride semiconductor laser element 701 so that the nitride semiconductor laser element 701 surrounded by the submount 703 and the heat sink 711 can be electrically connected to an external member, that is, because the electrode 708 needs to be provided between the nitride semiconductor laser element 701 and the base 715 to connect the lead 717 and the nitride semiconductor laser element 701 by a fine gold wire 709. Thus, the distance between the nitride semiconductor laser element 701 and the base 715 is increased, and the length of a heat dissipation path is therefore also increased. As a result, the heat dissipation properties of the semiconductor light-emitting device 700 are deteriorated.
Patent Document 2 (Japanese Unexamined Patent Publication No. 2009-076730) and Patent Document 3 (Japanese Unexamined Patent Publication No. 2004-103735) disclose a configuration in which a heat sink itself serves as an electric interconnect. For example, FIG. 9 is a conventional semiconductor light-emitting device 800 having a structure in which a plurality of nitride semiconductor laser elements 801 are sandwiched and held between a conductive first submount 802 and a conductive second submount 804, with solder materials 803, 805 interposed therebetween. The first submount 802 and the second submount 804 are adhered to the base 806 with a solder material (not shown). The first submount 802 and the second submount 804 are provided on the base 806, and are respectively connected to two conductive regions electrically insulated from each other.